1. Field Of The Invention
This invention relates to a mount assembly for a caster wheel of the type provided for supporting an agricultural implement, or at least a part thereof, as the implement travels over the terrain.
2. Description Of The Prior Art
Numerous types of agricultural implements are provided with support wheels for supporting a part of an implement such as a swather or combine header which is mounted on a hydraulic lift system at the front of a tractor or combine unit. The headers have considerable width transverse to the direction of travel relative to the width of the propelling unit, and supporting wheels, commonly called gauge wheels, are provided adjacent the outer ends of the header. The gauge wheels have commonly been mounted on an arm which is connected at a front end to a frame member of the header, the arm having a wheel spindle at its rear end, the spindle projecting in a direction transverse to the direction of travel. The gauge wheel is mounted for rotation on the spindle. With this simpler form of mounting for the gauge wheel, it is apparent that there is an excessive amount of side scuffing of the wheel with the ground when the implement is being manoeuvered through a turn. This is particularly true in relation to the tire of the gauge wheel at the inside of a turn where it is not unusual during a short turn for the tire of the inside wheel in the turn to actually gouge the field. Even during a short turn, the tire of the gauge wheel on the outside of the turn usually does not present a problem because its radius of turn is much larger. Thus, it is not necessary for the outside gauge wheel to caster in a turn. In any event, because of the difficulty experienced by the wheel on the inside, there is not only excessive wear and potential damage to the tire and wheel, but considerable strain is also put on the mounting arm and its pivot connection to the frame. Another problem which is present is some caster wheel designs is that in straight ahead travel the wheel is affected by the surface of the ground to the extent it does not track truly.
While caster type wheels which are mounted to allow free 360 degree revolving of the wheel about a substantially vertical axis are used on some implements, such an arrangement is not particularly feasible in implements such as headers as the mounting position for such a caster wheel would have to be a considerable distance behind the header for clearance during its revolving action. Another alternative which is known involves a wheel mounted on an assembly which turns about a substantially vertical axis, and wherein the steer is controlled by a powered steering mechanism, such as one using a hydraulically operated cylinder. Such an arrangement and any associated automatic control adds considerably to the cost of the implement as well as to its maintenance costs. An apparatus of a type including a mechanism for locking a castor wheel other than when cornering is shown in Canadian Patent No. 1,331,842, Jeannotte, Sep. 6, 1994.